Characterization of a solventless injection interface for supercritical fluid chromatography

Characterization of stationary phases in supercritical fluid chromatography including exploration of shape selectivity

New psychoactive substances represent serious social and health problem as tens of new compounds are detected in Europe annually. They often show structural proximity or even isomerism, which complicates their analysis. Two methods based on ultra high performance supercritical fluid chromatography and ultra high performance liquid chromatography with mass spectrometric detection were validated and compared. A simple dilute-filter-and-shoot protocol utilizing propan-2-ol or methanol for supercritical fluid or liquid chromatography, respectively, was proposed to detect and quantify 15 cathinones and phenethylamines in human urine. Both methods offered fast separation (<3min) and short total analysis time. Precision was well <15% with a few exceptions in liquid chromatography. Limits of detection in urine ranged from 0.01 to 2.3ng/mL, except for cathinone (5ng/mL) in supercritical fluid chromatography. Nevertheless, this technique distinguished all analytes including four pairs of isomers, while liquid chromatography was unable to resolve fluoromethcathinone regioisomers. Concerning matrix effects and recoveries, supercritical fluid chromatography produced more uniform results for different compounds and at different concentration levels. This work demonstrates the performance and reliability of supercritical fluid chromatography and corroborates its applicability as an alternative tool for analysis of new psychoactive substances in biological matrixes.

Effects of high concentrations of mobile phase additives on retention and separation mechanisms on a teicoplanin aglycone stationary phase in supercritical fluid chromatography

Imprinted polymers for chiral resolution of (±)-ephedrine, 4: Packed column supercritical fluid chromatography using molecularly imprinted chiral stationary phases

Contribution of supercritical fluid chromatography to serially coupling columns for chiral and achiral separations

This paper presents a review of the literature covering separations of enantiomers achieved with supercritical fluids. Supercritical fluid chromatography (SFC) is the main technique represented but chiral extraction (chiral SFE) and simulated moving bed (SMB) are also present. First of all, a historical view of the technique is presented. Then stationary phases, mobile phases and operating conditions are discussed, with a particular focus on the effect of operating parameters on the resolution. Detection issues are presented. The interest of SFC for screening methods and for the preparative scale is demonstrated. Comparison with other chromatographic techniques, namely gaseous-phase chromatography (GC) and high-performance liquid chromatography (HPLC) is provided. While the pharmaceutical industry is the principal application area of enantioselective separations, other examples with agrochemicals or fragrances are also presented. Foreword: This article focuses on main developments in the field of chiral separations with supercritical fluid chromatography and related techniques, as well as representative applications. It is not intended to be a comprehensive review of all papers published on the topic of chiral separations with supercritical fluids. However, it is believed that the publications mentioned here are representative of the evolution of the technique over more than 25 years of use. Several excellent reviews covering other aspects of chiral separations and/or supercritical fluid chromatography are also mentioned where appropriate. Keywords: Chiral resolution, chiral stationary phases, enantiomer separation, packed column, simulated moving bed, supercritical fluid chromatography.

Calculation of pressure, density and temperature profiles in packed-column supercritical fluid chromatography

Packed-column supercritical fluid chromatography (SFC) is coupled to capillary gas chromatography (GC) and applied to the analysis of complex petroleum fractions. The SFC system employs an electronically controlled back pressure regulator to allow independent control of flow and pressure. The SFC eluant is split after the stationary phase column with a fraction directed to a flame-ionization detector with a fused-silica restrictor. The remainder of the eluant passes through an ultraviolet detector after which it can be further split via a three-way valve to allow selected fractions to be «cut» into the GC split injector where they can be cryofocused onto the GC column

Evaluation of temperature and pressure effects on retention in supercritical fluid chromatography on polar stationary phases

Effect of ionic additives on the elution of sodium aryl sulfonates in supercritical fluid chromatography

Previous chapters have described the on-line coupling of supercritical fluid extraction (SFE) with a variety of chromatographic techniques, including: gas chromatography (GC), capillary supercritical fluid chromatography (cSFC), packed column supercritical fluid chromatography (SFC) and high-performance liquid chromatography (HPLC). Three major advantages of coupling SFE with chromatography are that: all of the extracted analytes can be transferred (if required) to the chromatographic system, this being particularly valuable in the case of ultra-tracelevel studies provided robust on-line SFE procedures can be developed, considerable savings in analyses times can be achieved potential errors associated with off-line sample preparation manipulations can be eliminated.

The plasma emission detector (PED) has been shown to be an element specific detector for supercritical fluid chromatography (SFC). The commonly used eluents (CO2 and N2O) tend to disturb the He plasma; two different discharge tubes were tested in an attempt to overcome this problem. Promising results were obtained with a concentric dual flow torch design for the element specific detection of Cl, H, and C containing analytes using N2O as SFC mobile phase.

The retention behavior of polycyclic aromatic hydrocarbons (PAHs) in packed‐column supercritical fluid chromatography (SFC) is studied for monomeric and polymeric C18 columns. Molecular shape discrimination (shape selectivity) is assessed through the use of Standard Reference Materials (SRMs), adn changes in selectivity are studied as a function of temperature, pressure, and mobile phase composition. Examples of separations of complex PAH isomer mixtures are presented, and guidelines are provided for modification and optimization of shape selectivity in SFC.

Monitoring polycyclic aromatic hydrocarbons in waste gases

Analysis of felodipine by packed column supercritical fluid chromatography with electron capture and ultraviolet absorbance detection